It is well known and understood that computer systems, whether stand alone desktop units or large networked systems, are comprised of a number and variety of different types of components or units, each of which is designed to fulfill certain purposes or a range of purposes. For example, the primary units in a computer system are general purpose processing units comprised of one or more general purpose processors, memory or non-volatile storage devices that are designed and intended to perform a range of data manipulation tasks, such as document or image processing and editing, data management, and so on. Other components of such systems, however, are primarily designed to perform more specific tasks or a more specific range of tasks, such as communications servers, file servers, printers, and so on. Unlike general purpose processing units, which are intended to perform a range of often disparate tasks and are thus typically program controlled, with their function at any time being controlled by the programs, specific function units have tended to be less programmable. That is, and even though specific function units have typically been implemented with many of the components used in general purpose processing units, such as programmable processors, memories, and so on, as well has the hardware components specific to their intended functions, specific function units have typically not been provided with the “programmable” capabilities of general purpose processing units. That is, the general purpose processing elements of specific function units have normally been controlled by programs residing in the general purpose processing units, such as printer driver programs residing in personal computers, or by programs stored in the specific function units in various forms of permanent, unchangeable memory, such as ROMs (Read Only Memories).
While limiting the flexibility and adaptability of such specific function units, and making upgrades or changes in function more difficult by requiring the replacement of a physical component such as a program ROM with another physical component, this principle has been advantageous in allowing greater control over the distribution of the programs used to control the functions of such units. That is, the programs that control the functions and operations of any device in a computer system may exist in either of two forms, either as hard-wired programs residing, for example, in ROMs, or as transportable programs residing, for example, on hard disks. A fundamental distinction between these two forms is that transportable programs may be readily moved, copied, downloaded, and so on, and are thus readily subject to unauthorized copying or use while hard-wired programs are significantly more difficult to copy or otherwise use for unauthorized purposes. In the methods of the prior art, therefore, the majority of programs that were implemented in transportable form resided in the general purpose processing units, which formed the minority of units in a computer system so that the transportable programs were more subject to effective control. In contrast, the programs controlling the more numerous specific purpose units were “non-transportable”, either resided in the specific function units as hard-wired programs and thus being significantly harder to copy or residing in the general purpose processing units and thus being subject to the same controls as other programs in the general purpose processing units.
More recent trends in computer systems, however, including both stand-alone desktop systems or large networked systems, have been to implement specific function devices as fully or extensively programmable devices in the same manner as general purpose processing units, with the additional components necessary to their primary functions, such as communications controllers or print mechanisms. This approach provides a significantly greater degree of adaptability and flexibility to the units, allows the range and complexity of tasks that each can perform to be readily increased or modified, and allows upgrades, modifications and the addition of functions by program loading rather than by replacement of hardware components. This, however, has necessitated in the control programs for such devices and units being implemented in the devices as “transportable” programs resident on hard disk or in other forms of readable and writeable storage. As a result, the control programs for specific function devices are significantly more susceptible to copying or other unauthorized use and are notable more difficult to protect from unauthorized uses. This, in turn, is a matter of concern to both the creators of such control programs and the manufacturers of computer systems that incorporate third party programs.
The present invention provides a solution to these and other related problems of the prior art.